./lxc-debian -p /var/lib/lxc/name_of_container

Useful resource:
blog.foaa.de/2010/05/lxc-on-debian-squeeze

!!! Error reading from database !!!
!! Illegal mix of collations (utf8_general_ci,IMPLICIT) and (utf8_unicode_ci,IMPLICIT) for operation '='
SELECT po.id AS oldpage_id, po.pagename AS oldpage_pagename, po.version, po.flags,
                   po.content, po.author, po.userid AS oldpage_userid, po.created, po.lastmodified, po.refs, po.meta, po.hits, po.wiki,
                   p.id AS newpage_id, p.subwikiid, p.title, p.cachedcontent, p.timecreated, p.timemodified AS newpage_timemodified,
                   p.timerendered, p.userid AS newpage_userid, p.pageviews, p.readonly, e.id AS entry_id, e.wikiid, e.course AS entrycourse,
                   e.groupid, e.userid AS entry_userid, e.pagename AS entry_pagename, e.timemodified AS entry_timemodified,
                   w.id AS wiki_id, w.course AS wiki_course, w.name, w.summary AS summary, w.pagename AS wiki_pagename, w.wtype,
                   w.ewikiprinttitle, w.htmlmode, w.ewikiacceptbinary, w.disablecamelcase, w.setpageflags, w.strippages, w.removepages,
                   w.revertchanges, w.initialcontent, w.timemodified AS wiki_timemodified,
                   cm.id AS cmid
              FROM wiki_pages_old po
              LEFT OUTER JOIN wiki_entries_old e ON e.id = po.wiki
              LEFT OUTER JOIN wiki w ON w.id = e.wikiid
              LEFT OUTER JOIN wiki_subwikis s ON e.groupid = s.groupid AND e.wikiid = s.wikiid AND e.userid = s.userid
              LEFT OUTER JOIN wiki_pages p ON po.pagename = p.title AND p.subwikiid = s.id
              JOIN modules m ON m.name = 'wiki'
              JOIN course_modules cm ON (cm.module = m.id AND cm.instance = w.id)

Summed up — an “Illegal mix of collations” was occurring while querying the table wiki_pages_old. A quick search found a possible solution. Unfortunately (for now) I’m not really sure if it helped, since the error persisted, but it is worth of making a note of it until being sure (by migrating the production server).

So I went in with phpMyAdmin and changed the collation on the table manually, which didn’t help either, since it didn’t change the collation of the individual fields. So I changed the fields’ collation manually, except for one field, which — after changing the collation — started to report a duplicate entry. After some trial and error I’ve found a solution.

From the table dump file I’ve deleted the offending key and after importing the table into the database I’ve searched for the offending duplicate entries.

The following MySQL query, from MySQL forum, finds the duplicate entries.

SELECT t1.* FROM t1 INNER JOIN (
SELECT colA,colB,COUNT(*) FROM t1 GROUP BY colA,colB HAVING COUNT(*)>1) as t2
ON t1.cola = t2.cola and t1.colb = t2.colb;

In my case the upper query changes into this:

SELECT wiki_pages_old.* FROM wiki_pages_old INNER JOIN (
SELECT pagename,version,wiki,COUNT(*) FROM wiki_pages_old GROUP BY pagename,version,wiki HAVING COUNT(*)>1) as wiki_t2
ON wiki_pages_old.pagename = wiki_t2.pagename and wiki_pages_old.version = wiki_t2.version and wiki_pages_old.wiki = wiki_t2.wiki;

I’ll write some more details after migrating the production server.

Any video/audio to OGG/Vorbis

fmpeg -i source.file -vn -acodec libvorbis -aq 6 audio.ogg

The -vn option disables video recording — omit if source is audio file. The -aq option stands for audio quality. The value of 6 results roughly at 192 kbit/s. For other values check this table.

Any audio/video to mp3

ffmpeg -i source.file -vn -ar 44100 -ac 2 -ab 192 -f mp3 sound.mp3

The -vn option disables video recording — omit if source is audio file; -ar sets the audio sampling frequency; -ac number of audio channels; -ab audio bitrate in bit/s; -f forces mp3 format.

$ ./configure
$ make
# checkinstall -D make install

You’ll end up with installed package or deb package to install with dpkg. In either case you can simply remove the package and all it’s files with apt-get or other package manager..

References:

• www.linuxquestions.org

• ubuntuforums.org

Installing it on Debian is easy:
apt-get install logwatch

On my virtual Debian host there was no configuration file in the expected place so I copied it from /usr/share/logwatch/default.conf folder:
cp /usr/share/logwatch/default.conf/logwatch.conf /etc/logwatch/conf/

Things you must change in this file are:

• Output = mail
• MailTo = your.mail@example.com
• Detail = High

The rest is optional and subject to your needs. The logwatch.conf is well documented.

Create folder /var/cache/logwatch needed by logwatch as specified in logwatch.conf.
# mkdir /var/cache/logwatch